[PATCH 14/16] sh: mm: Support MAP_BELOW_HINT
From: Charlie Jenkins <hidden>
Date: 2024-08-28 05:50:14
Also in:
linux-arch, linux-kselftest, linux-mips, linux-mm, linux-riscv, linux-s390, linux-sh, lkml, loongarch, sparclinux
Subsystem:
superh, the rest · Maintainers:
Yoshinori Sato, Rich Felker, John Paul Adrian Glaubitz, Linus Torvalds
Add support for MAP_BELOW_HINT to mmap by restricting high_limit to addr when the flag is enabled. Signed-off-by: Charlie Jenkins <redacted> --- arch/sh/mm/mmap.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index bee329d4149a..867f6598b7d0 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c@@ -91,6 +91,8 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, info.length = len; info.low_limit = TASK_UNMAPPED_BASE; info.high_limit = TASK_SIZE; + if (flags & MAP_BELOW_HINT) + info.high_limit = MIN(info.high_limit, addr + len); info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0; info.align_offset = pgoff << PAGE_SHIFT; return vm_unmapped_area(&info);
@@ -141,6 +143,12 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, info.length = len; info.low_limit = PAGE_SIZE; info.high_limit = mm->mmap_base; + if (flags & MAP_BELOW_HINT) + /* + * Subtract (STACK_TOP - mm->mmap_base) to get random + * offset defined in mmap_base() in mm/util.c + */ + info.high_limit = MIN(info.high_limit, (addr + len) - (STACK_TOP - mm->mmap_base)); info.align_mask = do_colour_align ? (PAGE_MASK & shm_align_mask) : 0; info.align_offset = pgoff << PAGE_SHIFT; addr = vm_unmapped_area(&info);
@@ -156,6 +164,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, info.flags = 0; info.low_limit = TASK_UNMAPPED_BASE; info.high_limit = TASK_SIZE; + if (flags & MAP_BELOW_HINT) + info.high_limit = MIN(info.high_limit, addr + len); addr = vm_unmapped_area(&info); }
--
2.45.0